Patent GB-1181461-A (GB)
Title: A Power Operated Tool
Inventor: HOZA MARTIN DAVID
IPC: B25B23/145
Filed: 1967-03-03
Abstract: 1,181,461. Nut runners. REED INTERNATIONAL Inc. 3 March, 1967, No. 10203/67. Heading B3N. A fluid-operated nut runner comprises an impact mechanism 6, 10, Fig. 1, which effects an initial torque, and means for automatically limiting the subsequent rotation of the impact mechanism so as to provide a final tightening of the nut. Hammer 10 is splined into the rotor 8 of an air motor 7, and is spring-urged away from anvil 4. A roller 12 mounted in the rotor co-operates with a cam 11 connected to a shaft 24 so as to provide relative limited rotational movement. A cylinder 27 is secured to the tool housing 3, Figs. 8 and 9, a valve actuator 28 is rotatably located in the cylinder, and a sleeve 29 is mounted on the cylinder and is arranged for limited rotation therewith. An inflatable clutch assembly comprises an inner sleeve 31 splined to shaft 24, and a resilient sleeve 33 secured in air-tight fashion to sleeve 31. A spindle 35 is mounted within sleeve 31, and a clutch spring 38 has its ends connected to sleeve 29, and to cylinder 27, Fig. 8. A ring 43, Figs. 1 and 4, is mounted on valve actuator 28 and is connected thereto by a torsion spring 45, a stop-pin 48 on the actuator being adapted to engage with a projection 43a on the ring, Fig. 7, the relative position of the pin and projection being varied by a worm 50, Fig. 4, which co-operates with teeth on the ring. A valve 53, Figs. 1, 3, is actuated at certain times in the cycle by releasing a pin 57 due to engagement of a projection 65 on valve actuator 28, with a shoulder 64 on the pin. A valve 68, Fig. 2, is actuated by a lug 72 on sleeve 29, the position of which can be adjusted by a screw 74. In operation, trigger 16, Fig. 1, is depressed, and compressed air passes through a valve 17, reversing valve 20, and into motor 7, to effect clockwise rotation of the nut. As motor 7 rotates, rotor 8 carries roller 12 along with it, and cam 11 rotates. When a predetermined resistance is encountered anvil 4 slows down, roller 12 moves over a lobe on cam 11 causing the hammer 10 to move forward to thus produce an impact. The hammer rebounds, spring 13 moves it rearwardly, the rear end 26 of the rotor carries sleeve 29 in a counter-clockwise direction through spring 38, Fig. 8, until lug 72 engages stem 69 of valve 68, Fig. 2. When the rebound reaches a certain travel, valve 68 moves to permit pressurized air to flow from passage 77, to passages 76, 78, and thence to clutch assembly 30 through passages 80-83. Sleeve 33 expands and frictionally engages within the valve actuator 28 so as to cause the latter to rotate with shaft 24. The nut is further tightened, and actuator 28 rotates a predetermined amount until projection 65, Fig. 3, actuates valve 53 which stops the air supply to the motor. In a modification, the arrangements for shutting off the air to the motor comprises a valve 105, Figs. 10, 11, which is tripped by a pin 114 on valve actuator 28a, which engages a pin 113. When the nut runner is operated in an unscrewing direction the clutches are inoperative and the runner operates as a normal impact nut runner.